In the past, electric lawn tractors and electric riding mowers can roll away if the operator exits the vehicle without properly and safely securing the vehicle. For example, electric lawn tractors may roll down a slope if the operator leaves the vehicle without placing the transmission in park and/or setting the park brake.
Automatic parking brake systems on vehicles such as golf carts have not been satisfactory for roll away prevention of electric lawn tractors because they require a controller and/or electrical system to remain in an active, power consuming state out powering down. As a result, automatic parking brake systems drain batteries needed to operate the vehicle and to continue operating the automatic parking brake system, U.S. Pat. Nos. 7,332,881, 7,560,882, 7,825,615 and 8,120,291 are examples of automatic, parking brake systems. Systems that prevent removal of the ignition key until the vehicle is safely parked and the park brake is engaged also have not been satisfactory because they do not prevent the vehicle from rolling away it the operator leaves the ignition key in place. U.S. Pat. No. 5,975,648 relates to one of these systems for passenger vehicles. Systems on passenger vehicles that include wheel speed or drive shaft rotation sensors also are not satisfactory for roll away prevention of electric lawn tractors because they increase the cost and complexity of the vehicle.
A simple and economical electric lawn tractor roll away prevention system and method is needed that does not require the vehicle to remain in an active, power consuming state, but that allows powering down the vehicle controller and/or electrical systems. An electric lawn tractor roll away prevention system is needed that prevents the vehicle from roiling away even if the ignition key is in place. An electric lawn tractor roll away prevention system is needed that does not require additional sensors to detect movement of the vehicle.